If I touch within the container field, the container field becomes highlighted. I do not get an option to use the camera (or to do anything actually). If I hold my finger down longer within the container field, I get the option to paste a picture into the field.

This sounds very familiar, but I can't seem to find a relevant record in our issues database for FileMaker Go 12. If I recall correctly, tapping Paste should give you an option to Replace with the the option for Camera. Can you confirm?

Is there a reason why you are not using FileMaker Go 13 or FileMaker Go 14?